In the field of wireless communication according to wireless cellular technology standards like 3GPP (UMTS, LTE, and following) there is a growing problem of hackers who try to disturb the cellular networks at their most vulnerable component: the air interface. It is known that those disturbances comprise in particular a jamming of a certain frequency range. With such jammers it is in particular possible to compromise security installations, in particular theft tracking units on a car or the like. Such a theft tracking unit is equipped with a wireless communication unit, in particular a machine-to-machine (M2M) module operating within cellular networks. Those units are configured to send a message to a security center, when the car is cracked or moved without key etc. With a jamming transmitter the ability of a common theft tracking unit to send an alert to the security center is disturbed, which results in a theft tracking unit being practically inoperative.
Therefore there is a need for methods to detect the situation of inoperativeness in order to warn the owner differently. It is in particular necessary to distinguish a jamming attack from the mere unavailability of cellular networks supported by the present device, e.g. in a parking garage or on a sea ferry.
Known solutions to solve the addressed problem are in particular oriented on frequency-division cellular network technology standards (FDD), which are characterized by the fact that the uplink and the downlink channels have separate frequency ranges.
What is still missing is a solution which is applicable to cellular networks according to time-division technology standards (TDD). Those cellular networks have the peculiarity that uplink and downlink traffic share the same frequency range. When a communication user equipment (UE) in a frequency-division cellular network cannot decode the downlink signaling from a base station, but can measure energy in the band, there is strong likelihood that a disturbance, in particular a jamming transmitter, is measured. For time-division based cellular networks the same situation is the normal situation, as other communication user equipment in the proximity could at the same time use the frequency range to conduct uplink communications. This cannot be decoded due to different coding schemes resp. scrambling codes. But this situation is unable to be used as an indicator for the presence of a jamming transmitter.
It is therefore a need for communication user equipments supporting time-division technology standards to find a new solution which can reliably distinguish the situation of a jamming transmitter affecting a communication user equipment from the normal situation and/or the situation of being out of service, in order to execute warning or other security measures.
Further alternative and advantageous solutions would, accordingly, be desirable in the art.